Supraventricular Tachycardia

Topic Overview

What is supraventricular tachycardia?

Supraventricular tachycardia (SVT) means that from time to time your
heart beats very fast for a reason other than exercise, high fever, or stress.
For most people who have SVT, the heart still works normally to pump blood through the body.

During an episode of SVT, the heart's electrical system
doesn't work right, causing the heart to beat very fast. The heart beats at
least 100 beats a minute and may reach 300 beats a minute. After treatment
or on its own, the heart usually returns to a normal rate of 60 to 100 beats a
minute.

SVT may start and end quickly, and you may not have
symptoms. SVT becomes a problem when it happens often, lasts a long time, or
causes symptoms.

What are the symptoms?

Other symptoms include near-fainting or fainting (syncope), shortness of breath, chest pain, throat
tightness, and sweating.

How is SVT diagnosed?

Your doctor will diagnose
SVT by asking you questions about your health and symptoms, doing a physical
exam, and perhaps giving you tests. Your doctor:

Will ask if anything triggers the fast heart
rate, how long it lasts, if it starts and stops suddenly, and if the beats are
regular or irregular.

May do a test called an
electrocardiogram (EKG, ECG). This test measures the
heart's electrical activity and can record SVT episodes.

If you do not have an episode of SVT while you're at the
doctor's office, your doctor probably will ask you to wear a portable electrocardiogram (EKG), also called an ambulatory electrocardiogram. When
you have an episode, the device will record it.

Your doctor also
may do tests to find the cause of the SVT. These may include blood tests, a
chest
X-ray, and an
echocardiogram, which shows the heart in motion.

How is it treated?

Some SVTs don't cause
symptoms, and you may not need treatment. If you do have symptoms, your doctor
probably will recommend treatment.

To treat sudden episodes of
SVT, your doctor may:

Prescribe a medicine to take when the SVT
occurs.

Show you how you can slow your heart rate on your own with physical actions. These actions are called vagal maneuvers. They include bearing down or putting an ice-cold, wet towel on your face. Bearing down means that you try to breathe out with your stomach muscles but you don't let air out of your nose or mouth. Your doctor might recommend that you do these actions while you lie down on your back.

If these treatments don't work, you may have to go to your
doctor's office or the emergency room. You may get a fast-acting medicine to slow your heart rate. If the SVT is serious, you may have
electrical cardioversion, which uses an electrical
current to reset the heart rhythm.

The goals of treatment are to prevent episodes, relieve symptoms, and prevent future problems. You and your doctor can decide what type of treatment is right for you. Your options may include:

Take medicine every day to prevent the
episodes or slow your heart rate.

Try catheter ablation. This
procedure destroys a tiny part of the heart that causes the problem.

What can you do at home to prevent SVT?

You can try some things at home to help prevent SVT by avoiding the things that trigger it. Examples of things you can try:

Cause

Two common types of
supraventricular tachycardia—atrioventricular reciprocating tachycardia (AVRT) and
atrioventricular nodal reentrant tachycardia (AVNRT)—are caused by an abnormal
electrical pathway in the heart and often occur in
people who do not have any other type of heart disease. What causes this
abnormal pathway might not be clear.

Heart surgery in the upper chambers of the heart, such as surgery for a congenital heart defect.

Symptoms

Symptoms of
supraventricular tachycardia include:

A racing or fluttering feeling in the chest
(palpitations).

Chest discomfort
(pressure, tightness, pain).

Lightheadedness or dizziness.

Fainting (syncope).

Shortness of breath.

A pounding pulse. You
may feel or see your pulse beating, especially at your neck, where large blood
vessels are close to the skin.

Sweating.

Tightness or fullness in the
throat.

Tiredness (fatigue).

Excessive urine
production.

What Increases Your Risk

Some lifestyle factors can
raise your risk of having an episode of
supraventricular tachycardia (SVT), such as overuse of
nicotine or alcohol, or use of illegal drugs, such as stimulants like
cocaine or methamphetamine.

Decongestants that contain stimulants
should also be avoided, including oxymetazoline (such as Afrin and other
brands) and pseudoephedrine (such as Sudafed and other brands). Doctors also
warn against using nonprescription diet pills or "pep" pills, because many
contain ephedra, ephedrine, the herb ma huang, or other
stimulants.

Congenital heart defects can raise the risk of having supraventricular tachycardia. Conditions that affect the lungs, such as
chronic obstructive pulmonary disease (COPD),
pneumonia,
heart failure, and
pulmonary embolism, can raise your risk for multifocal
atrial tachycardia (MAT), a type of supraventricular tachycardia.

Many experts believe that
Wolff-Parkinson-White syndrome may in some cases be
inherited. If you have a first-degree relative, which is a parent, brother, or
sister, with this disorder and he or she has symptoms, talk with your doctor
about your risk for this abnormal heart rhythm.

When to Call a Doctor

Call 911 or seek emergency services immediately if you have a fast heart rate and
you:

Faint or feel as though you are going to
faint.

Have severe shortness of breath.

Have chest
pain.

Have symptoms of a heart attack or stroke.

Call your doctor if you are having fluttering in your chest
(palpitations) that persists and does not go away quickly or if you have
frequent palpitations.

If you have a pacemaker

Call your doctor right away if you have symptoms that could mean your device is not working properly, such as:

Your heartbeat is very fast or slow, skipping, or fluttering.

You feel dizzy, lightheaded, or faint.

You have shortness of breath that is new or getting worse.

Who to see

Health professionals who can evaluate symptoms of a fast or irregular
heartbeat include:

Most people who have
supraventricular tachycardia need to see a
cardiologist or electrophysiologist for follow-up care.

Exams and Tests

An exact diagnosis is important
because the treatment you receive depends on the type of tachycardia you have.
Supraventricular tachycardia can sometimes be
diagnosed simply on the basis of a
medical history and physical exam and a few
simple tests. Tests that may be done to
monitor your heart and diagnose the type of fast heart rate that you have
include:

Electrocardiogram (EKG, ECG), which measures the electrical impulses in the heart. If an
electrocardiogram is done while the fast heart rate is occurring, it often
provides the most useful information.

Ambulatory electrocardiogram. A portable EKG, such as a Holter monitor, can record
your heart rhythm on a continuous basis, usually over a 24- to 48-hour period. If your
symptoms are infrequent, your doctor may use another type of ambulatory
electrocardiogram called a cardiac event monitor. When you have symptoms, you
activate the monitor, which records your heart rhythm.

Electrophysiology study. In this test, flexible wires are inserted into a vein, usually in
the groin, and threaded into the heart. Electrodes at the end of the wires
transmit information about the heart's electrical activity. Your doctor uses this information to see whether there is an extra electrical pathway inside the heart
and, if so, where it is located. Catheter ablation can be done during this test
to treat abnormal pathways and correct the supraventricular
tachycardia.

After finding tachycardia, your doctor may need to search
for its cause. The specific tests needed depend on the particular tachycardia.
These tests may include:

Treatment Overview

Your treatment for supraventricular tachycardia (SVT) depends on a few things. They include what type of SVT, how often you have episodes, and how severe your symptoms are. The goals of treatment are to prevent episodes, relieve symptoms, and prevent problems. You and your doctor can decide what type of treatment is right for you.

Supraventricular tachycardia is usually treated if:

You have symptoms such as dizziness, chest
pain, or fainting (syncope) that are caused by your fast heart
rate.

Your episodes of fast heart rate are occurring more
frequently or do not revert to normal on their own.

Treatment for sudden-onset (acute) episodes

When
episodes of
supraventricular tachycardia (SVT) start suddenly and
cause symptoms, you can try
vagal maneuvers. Your doctor will teach you
how to do vagal maneuvers safely. These are things such as bearing down or putting an ice-cold, wet towel on your face.

Your doctor may also
prescribe a short-acting medicine that you can take by mouth if vagal maneuvers
don't work. This allows some people to manage their SVT without having to visit
the emergency room repeatedly.

If your heart rate cannot be slowed
using vagal maneuvers, you may have to go to your doctor's office or the
emergency room, where a fast-acting medicine can
be given to slow your heart rate. If the arrhythmia does not stop and symptoms are severe,
electrical cardioversion, which uses an electrical
current to reset the heart rhythm, may be needed.

Ongoing treatment of recurring supraventricular tachycardia

If you have recurring episodes of
supraventricular tachycardia, you may need to take
medicines, either on an as-needed basis or daily. Medicine treatment may include
beta-blockers,
calcium channel blockers, or other
antiarrhythmic medicines. In people who have frequent episodes, treatment
with medicines can decrease recurrences. But these medicines may have side
effects.

Many people with supraventricular tachycardia have a
procedure called
catheter ablation. This procedure can stop the rhythm problem in most people. Ablation is considered safe, but it has some rare, serious risks.

Ongoing Concerns

If supraventricular tachycardia occurs in someone
who has significant
coronary artery disease, the heart may not receive
enough blood to keep up with the demands of the increased heart rate. If this
occurs, the heart may not get enough oxygen, potentially causing angina symptoms (such as chest pain or pressure) or a
heart attack.

Mild supraventricular tachycardia,
with short episodes that don't happen often, doesn't typically weaken the heart or lead to heart failure. But some people have a higher risk of getting heart failure, such as those who have a heart valve disease. If tachycardia is left untreated,
repeated and long episodes of tachycardia can lead to
heart failure (known
as a tachycardia-mediated cardiomyopathy). But this heart failure might be stopped, or reversed, if the supraventricular tachycardia is stopped with treatment.

Prevention

You can reduce your risk of having
episodes of
supraventricular tachycardia by avoiding certain
stimulants or stressors, such as nicotine, some medicines (for
example, decongestants), illegal drugs (stimulants, like methamphetamines and
cocaine), and excess alcohol.

If fast
heart rates continue, long-term medicines may be used to
help prevent a recurrence of the fast heart rate.

Living With Tachycardia

Home care includes
monitoring your
supraventricular tachycardia (SVT) and trying to slow your
heart when a fast heart rate occurs. To monitor your condition, you may find it
helpful to keep a
diary of your heart rate and your symptoms.

Your doctor may suggest that you try
vagal maneuvers—such as holding your breath and bearing down or
putting an ice-cold, wet towel on your face—to slow your heart rate. Your doctor will
help you learn these procedures so you can try them at home when your fast
heart rate occurs.

Check your pulse when you have symptoms, and record the
information in your diary. Be aware that if your heart is beating rapidly, it
may be hard to feel your pulse and get an accurate count of your actual
heart rate.

By keeping a diary of your heart rate and symptoms,
you may be able to identify stressors—such as drinking alcohol or smoking—that trigger episodes.

Also, it's usually important
to avoid overuse of nicotine or alcohol and the use of illegal
drugs, such as stimulants like cocaine, ecstasy, or methamphetamine.

Decongestants that contain
stimulants should also be avoided, including oxymetazoline (such as Afrin and
other brands) and pseudoephedrine (such as Sudafed and other brands). Doctors
also warn against using diet pills or "pep" pills, ephedrine, ephedra, the herb ma huang, or other stimulants.

For most people, moderate amounts of caffeine do not trigger SVT. So most people do not have to avoid chocolate, caffeinated coffee, tea, or soft drinks.

More information

Medications

If you have symptoms, medicines may be
used to treat
supraventricular tachycardia.

Medicine choices

For severe symptoms, such as
chest pain, shortness of breath, or feeling faint, you may be given fast-acting
antiarrhythmic medicines by health professionals in
the hospital emergency department, where your heart can be monitored.
Fast-acting antiarrhythmic medicines commonly used to slow the heart rate
during an episode include:

Long-term use of an antiarrhythmic medicine may also be
needed to reduce the chance of having more episodes of supraventricular
tachycardia or to reduce the heart rate during these episodes. Common medicines
used for this purpose include:

Surgery

Open-heart surgery is rarely done for
supraventricular tachycardia. Surgery might be done if you cannot have catheter ablation or if you are having surgery for another heart condition.

Other Treatment

An electric shock to the heart
(electrical cardioversion) may be needed if you are having severe symptoms
of
supraventricular tachycardia and your heart rate does
not return to normal using
vagal maneuvers or fast-acting medicines.

A procedure called catheter ablation may
be done to try to stop SVT. During this procedure, the
extra electrical pathway or cells in the heart that are causing the fast heart
rate can often be identified and destroyed.

Epstein AE, et al. (2008). ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices): Developed in Collaboration With the American Association for Thoracic Surgery and Society of Thoracic Surgeons. Circulation, 117(21): e350–e408. [Correction in Circulation, 120(5): e34–e35.]

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